1. Field of the Invention
This invention relates to a method for forming a thin film, and a method for a thin film magnetic head using the forming method of thin film.
2. Related Art Statement
Conventionally, a writing magnetic pole portion of a thin film magnetic head is fabricated ad follows. First of all, a first magnetic film is formed on a given under layer, and a second magnetic film is formed on the first magnetic film via a gap film by a frame-plating method. Then, the gap film and the first magnetic film are trim-milled by using the second magnetic film as a mask, to form a trim-shaped writing magnetic pole portion.
In Japanese Patent Laid-open Publication No. Kokai Hei 2000-132812 (JP2000-132812) using the frame-plating method, such an attempt is made as to form a narrowed second magnetic film using a so-called three-layered resist, and thus, fabricate a narrowed writing magnetic pole portion.
In this case, an adhesive layer made of Ti or the like is formed on a gap layer, and then, an electrode film is formed on the adhesive layer. Thereafter, a first photoresist layer, an intermediate layer and a second photoresist layer having a thickness of 1 nm or below are formed in turn. Then, the second photoresist layer is exposed and developed with a mask, to fabricate a photoresist pattern having a minute opening. Then, the intermediate layer is partially etched by using the photoresist pattern as a mask, to fabricate an etching mask having a given opening.
Thereafter, the first photoresist layer is etched and removed by using the etching mask, to fabricate a photoresist frame. Then, the second magnetic film is formed in the photoresist frame by using the electrode film as an electrode.
In this case, the photoresist frame made of the first photoresist layer can be fabricated in self-alignment from the photoresist pattern made of the second photoresist layer. Therefore, the opening width of the photoresist frame can be set equal to the minute opening width of the photoresist pattern, and thus, the narrowed second magnetic film can be easily formed.
The intermediate layer is etched by a reactive ion etching (RIE) using oxygen gas. In this case, however, polymer debris may be created on the inner side surface and so on of the etching mask. The polymer debris can removed by using a solvent, but as a result, the etching mask itself may be damaged by the solvent. Therefore, the photoresist frame can not fabricated precisely, and thus, it is difficult to fabricate the writing magnetic pole portion by a frame-plating method.
The intermediate layer can be formed uniformly by a sputtering method. In this case, however, the first photoresist layer under the intermediate layer may be deteriorated, and thus, the photoresist frame can not fabricated in good condition by the etching process as mentioned above. Therefore, it is also difficult to fabricate the writing magnetic pole portion by the frame-plating method.